IEEE 802.16 is an emerging suite of standards for Broadband Wireless Access (BWA) commonly known in the wireless industry as WiMAX. WiMAX is one of the wireless technologies targeting the fourth generation of wireless mobile systems. The IEEE 802.16e amendment to the IEEE 802.16 base specification enables combined, fixed, and mobile operation in licensed and license-exempted frequency bands under 11 GHz. IEEE 802.16 defines the air interface used for data centric wireless networks. 802.16 is aimed at high mobility applications and designed to manage the quality of service (QoS) provided over the air.
The basic WiMAX network coverage is provided using an approach similar to other mobile wireless technologies (e.g., using high power macro base stations that may be grouped in a cluster of cells). In order to increase the intra-cell coverage and capacity, distributed small base station entities have been considered. Depending on the number of target users and the type of applications envisioned, these small base station entities have been defined by the WiMAX industry as nano, pico or femto base stations. Relay stations (RS) have also been introduced to extend radio coverage or to increase the throughput of a macro base station (mBS). An RS, which transfers data of active service flows between an mBS and mobile stations (MS), may be a low-cost alternative to an mBS.
The femto base station (fBS) is the smallest base station entity. An fBS is, in essence, a small WiMAX mBS that a user can purchase and install in his home or office. It provides the user's MS with the basic air interface functions of an mBS based on the IEEE 802.16 standard. Compared to an mBS, the fBS is a low-cost, low-power radio system that may be used by users in a relatively low mobility environment. The users can install the fBS in their building and connect it to their fixed broadband networks (e.g., cable, xDSL or DSL) to provide the fBS with its backhaul communication line. In this regard the fBS enables fixed/mobile convergence, providing the fixed user with mobility and increasing the spectral efficiency (e.g., improving the coverage) of the mobile user. Being located in the user's building, the fBS provides higher signal strength and better link quality than the MS would get from the mBS outside the user's building.